The BiosphereChapter 49

We have talked about predation, competition and species

interactions and how they affect the structure of

populations, communities and ecosystems.

This chapter considers the physical forces shaping the

biosphere itself…

Biogeography — the study of the distribution of

organisms, past and present, and of diverse processes that

underlie their distribution patterns.

Climate

Climate refers to the average weather conditions. Climate includes:

TemperatureHumidityWind velocityCloud coverRainfall

Climate

Climate is shaped by four factors:

(1) Variations in the amount of incoming solar radiation

(2) The earth’s daily rotation and path around the sun

(3) The world distribution of continents and oceans

(4) The elevation of land masses

These all interact to produce prevailing winds and ocean

currents that influence the global patterns of climate

Ocean Currentsare affected by:

1) Latitudinal and seasonal variations in solar heating, creating variations in temperature of ocean waters on a vast scale

2) Earth’s rotation / wind friction

Clockwise rotation - Northern hemisphere

Counterclockwise - Southern hemisphere

3) Position of land masses and shape of ocean basins

Climate zones correlated with surface currents & drifts

dry

tropical

warm temperate

cool temperate

cold

subpolar

polar (ice)

warm surface current cold surface current

Rain Shadow Effect

Rain shadow effect, a reduction of rainfall on the side of high mountains facing away from prevailing winds (aka leeward side).

Only plants adapted to arid or semiarid conditions grow in rain shadows.

Biome and Ecoregions

Biome is a large region of land characterized by habitat conditions and by its community structure.

Biome distribution corresponds w/ climate, topography and soil type

The form of the dominant plant tells us something of the weather conditions